gistfile1.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>


struct parent {
    int foo;
    char *bar;
};

struct child {
    struct parent ptr;
    char *extra;
};


struct parent *lefuu_construct(size_t size, int foo)
{
    struct parent *ret = malloc(size);
    
    /* Zone mémoire commune (meme offset) */
    ret->foo = foo;
    ret->bar = malloc(sizeof(char) * 1337);

    return ret;
}

void change_foo(struct parent *st, int foo)
{
    st->foo = foo;
}

int main(int argc, char **argv)
{
    
    struct parent *a = lefuu_construct(sizeof(*a), 42);
    struct child *b = (struct child *)lefuu_construct(sizeof(*b), 69);
    
    b->extra = NULL;

    printf("Foo val : %d\n", a->foo);
    printf("Child : %d\n", b->ptr.foo);

    change_foo(a, 1);
    change_foo((struct parent *)b, 2);

    printf("Foo val : %d\n", a->foo);
    printf("Child : %d\n", b->ptr.foo);


    free(a->bar);
    free(b->ptr.bar);

    free(a);
    free(b);

    return 1;
}